At the present time, substantially all earth and materials removed from leaking underground storage tank (LUST) remediation cites is disposed of in Type II, non-hazardous landfill sites. With the rising cost of solid waste disposal, the ever decreasing number of available landfill sites, and the increasing number of LUST remediation sites, the disposal of contaminated earth has become a very significant economic and environmental problem. The disposal of earth contaminated by petroleum products in landfills is, at the present time, the least expensive viable disposable alternative. However, disposal in landfills is acknowledged by several environmental agencies as the least environmentally favorable remedial action alternative. Even in Type II, non-hazardous landfill, some leaching inevitably occurs resulting in the petroleum products contained in the contaminated earth gradually evaporating into the atmosphere or leaching into the water system.
For some time, rotary cement kilns have been utilized for the purpose of disposing of hazardous organic waste and toxic metals. In the case of waste containing hazardous toxic metals, the toxic metals become encapsulated in the cement clinker and ultimately in the cement. At instances of high toxic metal concentration, the cement products are merely used to stabilize the waste and enable the waste to be disposed of in a hazardous landfill site. In other instances where the toxic metal content is relatively low, there have been proposals to actually utilize the toxic metal containing cement clinker to make commercial Portland cement. U.S. Pat. No. 4,984,983, Enkegaard, and U.S. Pat. No. 4,921,538, Lafser, Jr. et al., illustrate prior uses of rotary cement kilns in the disposal of toxic waste.
An object of the present invention is to reduce the volume of earth from LUST remediation sites which need to be disposed of in Type II landfills.
Another object of the present invention is to form Portland cement from clay, shale or sand removed from LUST remediation sites which are contaminated with petroleum products and are qualified as non-hazardous solid waste products pursuant to 40 CFR .sctn.261.4(d)(10) (Jul. 1, 1990 edition).
An advantage of the present process is that limited landfill space is not needlessly used by petroleum product contaminated clay, shale and sand, and the need to mine clay and shale to supply cement plants is also reduced.
These and other objects, features and advantages of the present invention will be readily apparent from the attached drawings and described in the accompanying specification.